In recent years, with the rapid development of convenient electronic components and parts in the field of mobile communication and mobile computer, small packaging and high-density assembly technologies have been considerably developed. Meanwhile, a series of rigor requirements are raised on the small packaging technology, for example, the packaging size is required as small as possible (particularly, the packaging height is smaller than smaller than 1 mm). The connection reliability after packaging shall be improved as much as possible so as to adapt to lead-free welding (protect the environment) and effectively reduce the cost.
For a long time, a single circle lead frame mode is always continued for QFN products due to the limitation of etching templates and etching process.
A QFN (Quad Flat No Lead Package) type multi-circle arranged and packaged integrated circuit packaging technology is a novel microminiature high density I/O packaging technology developed at home and abroad in recent years, and is one of the most advanced surface-mount and packaging technologies. It has the features of no lead, small area occupied by surface-mount and low installation height, and is a novel packaging technology which is rapidly developed for meeting the development demand of convenient electronic machines such as ultra-thin electronic products including PDA, 3G mobile phone, MP3, MP4, MP5, and the like, in the fields of mobile communication and mobile computer. However, the present quad flat no lead package has the defects of few leads (namely, few I/O), long welding wire, high welding wire cost, and limited frequency application, which cannot meet the demands of high density and multiple I/O packaging.